Nightly : Troubled by Triangles

[John Biddiscombe]

Will,

I'm afraid, I can't run the tcl script to check how my system behaves, but
it seems consistent.

------------

>I ran the attached Tcl script. It generates 28,000 reasonably complex
polygons taking 3.8 MByte. The result of the triangle filter is 168,000
triangles taking 6.636 MByte. The memory usage was reported by
vtkDataSet::GetActualMemorySize().

>The image size (as reported by the NT task manager) is  ~20MByte at the
conclusion of polygon generation. After the triangles are generated, the
image size is ~24.8MByte. (Of course this includes all the executable junk,
etc.)

------------

The actual memory consumption of the datasets is fine, before and after
completion. Here is a screen snapshot of the task manager and the filter
arrangement to show you what I mean.

http://www.rcru.rl.ac.uk/~jab/temp/screenshot_1.jpg

The polygons are cleaned thoroughly to ensure no dubious behaviour, they
are all closed/flattened to lie on xy plane, self intersections are removed
and then a cleanpolydata is run to ensure no degeneracies.

Executing the Triangle filter gives the output at the bottom of the screen.
You can see how memory rises from ~100MB right up, and then falls at 50%
(ish) then rises again and falls. On completion, the memory looks normal
and your memory consumption figures above are fine. It's during operation
that the problems arise.

I'm pressed for time today, but over the weekend, I'll step through the
trianglefilter code and try to see if I can locate a bug of any kind, or
see if there's something odd about my polygons.

John B





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